Question

Find the sum of all integers between 10 and 50 which leave remainder 2 when divided by 3

Answer 1

Answer:

Sum= 427

Step-by-step explanation:

AP is

11,14,17,.......,50

a=11

d=3

l=50

l=a+(n-1)d

50=11(n-1)3

39/3=n-1

13=n-1

n=14

Sum=n/2(a+l)

= 14/2(11 + 50)

= 7 (61)

= 427

Answer 2

Answer:

Step-by-step explanation:

11,14,17,20,23,.......47.

a=11,d=3

an=l=47

an=a+(n-1)d

47=11+(n-1)3

47=3n+8

3n=39

n=13.

Sn=n/2(a+l)

=13/2(11+47)

13/2(58)

=13×29

=377